1. Field of the Invention
The present invention relates to an image forming apparatus which forms images on a recording material using an electrophotographic system, such as a copier and a printer.
2. Related Background Art
Heretofore, in an image forming apparatus using an electrophotographic system, desired image formation is performed through a charging process for charging a surface of a photosensitive member, an exposing process for forming an electrostatic latent image on the surface of the photosensitive member by a light beam, a developing process for making toner adhere to the electrostatic latent image formed on the surface of the photosensitive member, and manifesting this into a toner image, a primary transferring process for primarily transferring a plurality of or monochrome toner image(s) formed on the photosensitive member with being superimposed on an intermediate transferring material, a secondary transferring process for transferring the toner image(s), which is primarily transferred on the intermediate transferring material, to a recording medium such as a sheet of paper, and a fixing process for performing the heat treatment and fusion of the toner image(s) transferred on the recording medium.
When transferring a toner image from the photosensitive member to the intermediate transferring material in the primary transferring process, toner not transferred remains on the photosensitive member. Since it is necessary to remove residual toner on the photosensitive member so as to prevent the residual toner from adhering at the time of subsequent image formation, the residual toner is removed using cleaning means providing a cleaning brush, a cleaning blade, etc.
In addition, since residual toner also adheres to an intermediate transferring material in the secondary transferring process similarly to the primary transferring process, it is necessary to remove the residual toner by cleaning means.
By the way, residual toner is also generated except when image formation is normally ended as described above. That is, since a toner image is not transferred to the recording medium when an image forming process is interrupted because of JAM, sheet empty, etc., more residual toner is generated than at the normal time.
In addition, generally, a conventional image forming apparatus forms a pattern image on a photosensitive member or an intermediate transferring material, and performs an adjustment control. Such pattern image is not transferred on a recording medium, but is removed by cleaning means as residual toner in a phase when the adjustment control ends. Such residual toner removed is recovered (or collected) into a waste toner vessel by waste toner recovering (or collecting) means.
By the way, when image formation like the above is repeatedly performed, the amount of waste toner in a waste toner vessel also increases gradually. Since there is a limit in the capacity of the waste toner vessel, when waste toner is recovered more than the capacity of the waste toner vessel, waste toner overflows from the waste toner vessel to pollute an inside of an apparatus, which may also give an adverse effect to image formation, or may damage the apparatus. Therefore, before the amount of waste toner recovered in the waste toner vessel becomes full, it is necessary to replace the waste toner vessel.
Then, a sensor which detects waste toner in a waste toner vessel is provided in the vessel, and when waste toner recovered becomes full, the sensor detects this to report this to a user by displaying this, while image forming operation is inhibited. Further, after the waste toner vessel being replaced, such a control that resumes image forming operation is performed.
In order to optimally perform a waste toner full detection control as mentioned above, it is desirable to comprise a sensor for detecting the amount of waste toner before capacity full (hereafter, this is called near-end) and a full detecting sensor for detecting that the vessel is full. By the near-end detecting sensor, it is possible to prompt the preparation of a waste toner vessel for replacement by notifying a user of that it is necessary to replace the waste toner vessel, and to prompt the replacement of the waste toner vessel with inhibiting image formation at the time of the capacity full which leads to a failure of an apparatus.
However, in order to achieve the miniaturization or cost reduction of an apparatus, it is required to reduce such sensors as the above. Then, a conventional apparatus comprises only a near-end detecting sensor, and performs the control of inhibiting image forming operation by forecasting the amount of waste toner after detecting near-end. As the means of forecasting the amount of waste toner, the technology disclosed in patent documents 1 through 3 (Japanese Patent Application Laid-Opens Nos. H11-119534, H11-344908 and 2000-231316) and the like has been already proposed.
The technology proposed in the patent document 1 is constituted so as to make a near-end signal outputted from toner recovery amount detecting means when the recovery amount of non-transferred toner in a recovery vessel reaches predetermined near-end amount, to start the detection of toner supply amount to a developing device by toner supply amount detecting means when this near-end signal is outputted, and to determine with control means that the recovery vessel becomes full in a stage in which the supply amount detected reaches the predetermined amount.
In the patent document 2, it is noted that counted values used for controlling an image forming apparatus with a predetermined value contained in a nonvolatile storage medium are different when forming an image in a first image formation mode and when forming an image in a second image formation mode. Then, since maximum values of waste toner contained in a containing machine differ, the above-mentioned first image formation mode and the above-mentioned second image formation mode are constituted so that different counted value according to image formation mode may be used.
Technology proposed in the patent document 3 is constituted so as to forecast the executable amount of image formation until a waste toner containing vessel becoming full on the basis of the image formation history when near-end position detecting means detects the near-end of the waste toner containing vessel, and to display that the waste toner containing vessel is full when the amount of image formation concerned reaches the forecast amount.
Nevertheless, all among the conventional technology with means of detecting the near-end of each waste toner vessel have following problems.
Thus, first, the technology for forecasting the amount of waste toner on the basis of image data or toner supply amount does not distinguish between the amount in the case where image formation is terminated normally, and the case where image formation is interrupted. As mentioned above, waste toner is generated also in the case of the interruption of image formation such as JAM and sheet empty. The amount of waste toner generated in the case where image formation is normally terminated and in the case where image formation is interrupted, such as JAM and sheet empty differs largely. In contrast to the amount of waste toner generated at the time of normally-terminated image formation being several tens percent of full toner images, there is more amount of waste toner generated at the time of image formation being interrupted, and for example, the toner of the amount which is equivalent to all the toner images at maximum is contained in a waste toner vessel as waste toner.
When the amount of waste toner at the time of abnormal image formation is treated similarly to that at the time of normal one when forecast is performed without distinguishing between the case of normal image formation and the case of interrupted image formation such as JAM and sheet empty (at the time of abnormality), there is more amount of waste toner than forecast amount, and hence, there is a high possibility that a waste toner vessel overflows. In addition, when it is forecast in consideration of a safety aspect that the amount of waste toner of all the images is similar to that at the time of JAM or sheet empty occurrence, a margin is left in the waste toner vessel, and hence, there arises a malfunction that image formation is inhibited although image formation is still possible.
A second problem is a respect of not estimating the amount of waste toner generated in an adjustment control of using a pattern image. For example, a color image forming apparatus which superimposes a plurality of toner images to form an image performs such a control of correcting the starting position of each color by forming pattern images for registration so as to superimpose each toner image correctly.
In addition, an image forming apparatus using two-component toner forms a pattern image, detects the density of the pattern image, and performs a correction control of a T/C ratio on the basis of the detection result, in order to set the T/C ratio (a ratio between toner and carrier) in a developing device.
As mentioned above, although the examples are given about adjustment means using pattern images, plenty of adjustment controls which use pattern images exist besides the above-mentioned examples. When not adding the amount of waste toner generated in these adjustment means in a forecast control, the actually contained amount of waste toner increases more than forecast amount, and there arises a possibility that waste toner overflows.
Furthermore, when the amount of waste toner is forecast on the basis of an image formation history and much JAM and sheet empty arise after near-end detection, the amount of waste toner may be estimated few. When a portion of an apparatus is failed, or when a part deteriorates, there may also arise many cases that image formation is suddenly interrupted by JAM and the like. Since a frequency of adjustment controls being performed also varies according to the aging and environment of an apparatus, it is difficult to say that the amount of waste toner is correctly forecast.